Goals¶

Goals are what you use to tell motors what to move towards. There are two kinds of goals: spring and instant goals. Spring goals replicate the motion of a spring, and allow you to specify a frequency and a damping ratio. Instant goals immediately move the motor to a value, and are useful for resetting a motor's value.

Goals are given to a motor using the motor's setGoal method. For group motors, you can specify a different goal for each value.

Spring goals¶

Spring goals use a model of a physical spring to animate towards a value over time. Spring goals animate faster for larger values automatically - moving over a small distance will visually move slower than moving over a large one. They also preserve velocity and will take time to decelerate. These two properties make your user interface feel more realistic and fluid.

Spring goals are created using the Otter.spring constructor. This constructor takes two arguments: the value to move towards and an optional table of parameters. This table supports two sets of configurations:

frequency and dampingRatio
- frequency: A number that represents how quickly the spring responds to changes. Higher values move faster, lower values move slower. Defaults to 1.
- dampingRatio: A number that represents how dampened the spring is. Defaults to 1.
stiffness, damping and mass
- stiffness: influences the number of “bounces” in the animation.
- damping: influences the level of spring in the animation.
- mass: influences the speed of the animation and height of the bounce.

Instant goals¶

Instant goals immediately move the motor to the goal. They're useful for resetting a value so that you can animate it again.

Instant goals are created using the Otter.instant constructor. This constructor takes one argument: the value to jump to.